[{"type":"SUCCESS","log":[{"visitor_id":"5ffff1354351be2c600c4f94","first_name":"Ayan","last_name":"Dey","mobile_number":"1234567890","visits":[{"_id":"5ffff3df82dc1a0e90d89a5c","in_time":"1610609615","out_time":"1610609671","checked_in_status":false,"visitor_id":"5ffff1354351be2c600c4f94","visit_purpose":"Test","person_to_meet":"Someone new","__v":0},{"_id":"5ffff41a82dc1a0e90d89a5d","in_time":"1610609615","out_time":"1610609730","checked_in_status":false,"visitor_id":"5ffff1354351be2c600c4f94","visit_purpose":"Test","person_to_meet":"Someone new","__v":0},{"_id":"5ffff45a82dc1a0e90d89a5e","in_time":"1610609615","out_time":"1610609919","checked_in_status":false,"visitor_id":"5ffff1354351be2c600c4f94","visit_purpose":"Test","person_to_meet":"Someone new","__v":0}]}]}]

db.collection.aggregate([{"$unwind":"$log"},{"$unwind":"$log.visits"},{"$sort":{"log.visits._id":-1}}])